Ki vagy, doki 9/4

The Doctor explains the Bootstrap Paradox to the audience, before landing in 1980 with Bennett and O'Donnell. They discover that the Tivolian, Prentis, is still alive, the writing has not yet been scratched into the wall, and that the spaceship is a hearse, carrying The Fisher King. Meanwhile, Clara, Cass and Lunn realise that The Doctor's ghost is uttering their names instead of coordinates. The Doctor contacts Clara and tries to reason with his ghost but it unlocks the Faraday cage, releasing the others. The Fisher King awakes, killing Prentis and writing the words on the wall. O'Donnell, Bennet and The Doctor flees but they get separated and O'Donnell is killed. The Doctor confronts the Fisher King, tricking him into leaving the church and the stasis chamber behind, and he uses the missing power cell to destroy the dam wall, flooding the base. The stasis chamber opens in the future to reveal The Doctor inside; his ghost is a hologram, programmed by The Doctor. The ghosts are sealed within the Faraday cage, and the Doctor and Clara leave. The Doctor asks Clara who thought of what to program the ghost to say, drawing a parallel with the Bootstrap paradox.